Water vapour atmosphere creation on Mars

Terraformer · 2024-07-04 15:50:09

In the Ceres thread, Calliban suggests launching water from Ceres to Mars to hypersaturate the atmosphere with water vapour which will be dissociated to produce oxygen:

Calliban wrote:

The presence of water on Ceres makes this sort of thing much more achievable.
In fact, Ceres may be key to terraforming Mars, as it is 10% water by mass. Suppose we mount mass drivers on the surface of Ceres. We launch packages of water ice in the opposite direction to Ceres orbital travel, so a portion of the orbital speed is cancelled out. They are given just enough velocity to reduce ther perogee such that it crosses Mars orbit. Eventually, these ice packages will collide with Mars exploding in its upper atmosphere. This will supersaturate the upper atmosphere with water vapour. In addition to creating a strong greenhouse effect, solar UV will break the water into hydrogen and oxygen. The former would rapidly escape Mars, with the oxygen being trapped and accumulating within the atmosphere.
We would need to deliver 7.2E17kg of water to the Martian atmosphere to produce a minimal breathable surface oxygen concentration. That is 82 million tonnes per hour, for 1000 years.

This would be a sizeable outgoing. Far easier would be to build mirrors and use Mars' own resources. Though it has far less water than Earth, Mars still possesses enough water to give it a ~70m layer globally (ignoring topography). If we were to use this as the sole source of oxygen, getting to a breathable amount would sacrifice less than 10% of this. To get above the triple point would take far less.

To raise ice from -60c to melting point would take ~130 MJ/tonne. To melt and then vapourise it would take far more, ~2600 MJ/tonne. Call it 3 GJ/tonne to make it easy.

How much mass do we need for 1mb of oxygen partial pressure on Mars? The surface area is ~1.5e14 m^2, and we would need ~25kg per square metre. So ~3.75e15 kg; accounting for the hydrogen we'd be getting rid of, call it 5e12 tonnes of water.

What if we wanted to add 1mb of atmosphere each year? There are ~3e7 seconds in a year, so we would need to be vapourising 5e12/3e7 tonnes per second. Call it 2e5, or 200,000 tonnes a second (ouch). Each tonne would take 3e9 J to liberate, so we would need a total power of... 6e14 W. 600 terawatts. That's a lot of power.

How big a mirror would we need? Insolation at Mars is ~600 W/m^2, so each square kilometre could provide 600 MW. 6e8 W. We would need 1e6, one million, square kilometres of mirror to provide for that level of power from sunlight. Not quite continent sized mirrors. But about five Britains worth. Yikes. But when reengineering planets that's a pretty minor task really.

(EDIT: I messed up a division and end up tripling it)

Last edited by Terraformer (2024-07-04 15:56:41)

tahanson43206 · 2024-07-04 17:12:18

This post is reserved for an index to posts NewMars members may contribute over time.

Best wishes for success with this ambitious new topic.

(th)

Terraformer · 2024-07-04 17:19:45

However. We do not need even 1mb to get substantial benefits from having some oxygen. Significant UV protection comes from ozone at 0.2mb (pretty sure this was in a Martian context). With 10,000 km^2 (1250 5km radius mirrors?), we could get that in two decades, at which point methane will be able to persist for far longer periods and provide global warming. There's still a lot of benefits to be had from even very trace atmospheres.

Calliban · 2024-08-12 12:17:48

This article discusses the use of nanorod dust as a substitute for flourine based greenhouse gases for producing atmospheric warming.
https://www.space.com/mars-terraforming … oparticles

The rods are sized to be larger than the visible spectrum of light, but shorter than infrared. This makes them 5000x more effective at trapping IR radiation (per unit mass) than the best performing greenhouse gases. About 20 million tonnes of rods in the atmosphere would result in a 30°C warming. The rods would have a halflife in the atmosphere of 10 years. The paper estimates a 700,000m3 annual production rate would be enough to sustain the concentration. That is about 80m3 per hour. That is achievable with a single modest sized factory.

If we were to make the rods from iron or aluminium as the article suggests, we would need several GW of power. I would propose the use of cast basalt fibres drawn through a rhodium die. Compared to iron, this would reduce the amount of power needed by a factor of 50, to about 140MW. This becomes a project that could be achieved by a Martian base of a few hundred people equipped with a small modular reactor.

If the surface temperature of Mars rises above the melting point of water, substantial water vapour would be released into the troposphere. Photolysis will begin to build up oxygen levels. Bacteria within the Martian soil will also break down perchlorates, releasing oxygen into the atmosphere. A mbar of oxygen may be all that is needed to start growing photosynthetic algae in open ponds.

Last edited by Calliban (2024-08-12 12:34:02)

Void · 2024-08-12 12:50:04

I don't think you need liquid water.

Such warming would warm the polar areas more than the equator, most likely, in the polar summers. (Not absolutely clear on that). This may create an imbalance where moisture would migrate to lower latitudes, perhaps as snow and frost. And of course it would also likely evaporate permanent CO2, increasing the atmospheric pressure warming things more, and bringing a bit more heat to the poles.

By increasing the ratio of exposed ice to ice covered with protective regolith/dust, a climate change effect of high clouds may occur.
https://news.uchicago.edu/story/icy-clo … tudy-finds
Quote:

Using a 3D model of the entire planet’s atmosphere, Kite and his team went to work. The missing piece, they found, was the amount of ice on the ground. If there was ice covering large portions of Mars, that would create surface humidity that favors low-altitude clouds, which aren’t thought to warm planets very much (or can even cool them, because clouds reflect sunlight away from the planet.)
But if there are only patches of ice, such as at the poles and at the tops of mountains, the air on the ground becomes much drier. Those conditions favor a high layer of clouds—clouds that tend to warm planets more easily.

Quote:

“Our model suggests that once water moved into the early Martian atmosphere, it would stay there for quite a long time—closer to a year—and that creates the conditions for long-lived high-altitude clouds,” said Kite.

So, you would be hoping to not only increase the evaporation of CO2 and so cause other effects such as albedo to warm the planet, but if you could increase the humidity of the atmosphere then you would be using H20 as a greenhouse gas as well, plus the insulating effects at night and winter of a high altitude cloud cover.

Not at all guaranteed, but it may be that a lesser warming would be enough to spread ice around in a manner useful to the goal.

Done

Last edited by Void (2024-08-12 13:02:13)

Calliban · 2024-08-13 12:26:32

It would appear that Mars has enough water to cover its entire surface to a depth of 1 mile.
https://news.berkeley.edu/2024/08/12/sc … ep-to-tap/

Unfortunately, it is trapped in crustal rocks at depths of 11.5 - 20km. This will make it difficult and expensive to access. The Kola borehole went down about 12km, from memory. It was halted by high temperature explosive mud which was bubbling with hydrogen at 180°C.

However, it is known that Mars has both a shallower geothermal gradient and shallower pressure gradient due to weaker gravity. This may make it easier to drill deeper. The pressure at the bottom of a 12km deep borehole on Mars would be only 38% the equivalent pressure on Earth. But this is clearly a significant project. It will be difficult and expensive to access the water as a resource.

Assuming we can eventually tap this water, there is more than enough here to build a breathable atmosphere on Mars, for which we need a global equivalent layer of 5m. There would appear to be at least 200x as much water as we would need to build a breathable oxygen atmosphere. Assuming we can drill to 11.5km, the pressure at that depth will exceed 100MPa due to the hydrostatic pressure of the rock. The water would be forced up the tube with enough driving pressure to reach the Martian stratosphere.

Last edited by Calliban (2024-08-13 12:57:12)

Void · 2024-08-14 09:07:44

I liked your post Calliban. I have hunted down some materials that may help a little to puzzle things out:

https://astrobiology.nasa.gov/news/evid … e-on-mars/
Rather old article: https://astrobiology.nasa.gov/news/wate … after-all/
https://en.wikipedia.org/wiki/Water_on_Mars
Far down in this article:
Subglacial liquid water
Main article: Subglacial lakes on Mars
Permafrost, Mars: https://link.springer.com/chapter/10.10 … -5418-2_38
Quote:
Calculations based on the Viking Mission Data indicate that permafrost thicknesses range from about 3.5 km at the equator to approximately 8 km in the polar regions. The depths to the bottom of Martian permafrost are more than three times the depth characteristic of permafrost in terrestrial polar locations.

So, if we accept as true that there is a deep layer of fractured rock infiltrated with water below the bottom of the Permafrost area, I think we can suppose that an atmosphere may exist above the fractured rock water and the bottom of the permafrost. That would be in the pore/fracture space above the deep water spoken of. Otherwise, some pore fracture space in that in-between area might have water fill of some kind.

So, we don't know if the subglacial lakes on Mars interact with the deep areas below the permafrost.

So, I have a suspicion of water lenses deep in the interior of Mars: https://en.wikipedia.org/wiki/Lens_(hydrology)
Quote:

freshwater lens
A freshwater lens is a convex-shaped layer of fresh groundwater that floats above the denser saltwater and is usually found on small coral or limestone islands and atolls1. When precipitation recharge across an atoll island is sufficient, a fresh groundwater lens (FGL) will form, with freshwater floating above denser, saline groundwater derived from the sea2.

Two methods I think might work in the void spaces above the underground sea, and the permafrost cap, might be freeze thaw and evaporation precipitation.

Both of these could lead to the stratification of salt water into layers, with the heaviest settling in on the bottom and the fresher on the top.

Freeze/Thaw might not work, as we have a sandwich of (We don't know) conditions between permafrost on top and salt water in fractured rock below.

Precipitation might work slowly. Of course, if evaporation occurred on the top of the fractured rock layer, and what was above was some type of void spaces filled with gasses, then water vapor moving up might condense to fresh water below the permafrost and then move downward by gravitation.

So, if we go down below the Permafrost, we might encounter a mixture of gasses which could include water vapor or water condensate, and also other gasses could include Hydrogen and Methane. I only say "Could".

So, near the equator that is 3 km down.

Could the drill hole be kept open by flowing an electric current through it?

I make note that if you can get Hydogen and Methane from it, then you can get water from it.

Done

Last edited by Void (2024-08-14 09:33:44)

Void · 2024-08-14 09:41:55

The materials of my previous post may try to indicate how the subsurface of Mars might support the topic here: " Water vapour atmosphere creation on Mars"

If it is true that Natural Hydrogen and maybe Methane may exist under the permafrost, then it would not be so much a concern to use ices which exist on the surface of Mars to attempt to increase the Oxygen content of the Martian atmosphere by injection of water vapor into the upper atmosphere of Mars.

Done

Calliban · 2024-08-14 11:18:44

Void wrote:

The materials of my previous post may try to indicate how the subsurface of Mars might support the topic here: " Water vapour atmosphere creation on Mars"
If it is true that Natural Hydrogen and maybe Methane may exist under the permafrost, then it would not be so much a concern to use ices which exist on the surface of Mars to attempt to increase the Oxygen content of the Martian atmosphere by injection of water vapor into the upper atmosphere of Mars.
Done

Agreed. TH raised the point that the deep crustal water may be soaked into mud, which has low viscosity. If so, it would be very difficult to bring it to the surface. I wonder if there are areas where water is in solid bedrock that can be hydraulically fractured?

To build a breathable atmosphere on Mars, we need 5 tonnes of water per square metre of surface. That is 720,000 cubic km. That is about 1/8th of the water known to be frozen as ice and only 1/300th of the estimated crustal water resource.

If we can find deep water or mud that has sufficiently low viscosity, the pressure of the overlying rocks should be sufficient to force it to the surface. We could also use water jets to cut through the mud creating a slurry, which would be pushed up the tube. The slurry would be dumped into settling ponds, allowing the sludge to sink and the water to be retrieved. Most of the water would be reinjected, but a fraction could be harvested.

Last edited by Calliban (2024-08-14 11:32:35)

Void · 2024-08-14 11:38:08

A good question. We will have to learn what the rules of things are in the Mars undersurfaces.

But until then I would have a very hard look at Candor Chaos as a relatively easy place to set up initial activities.

https://www.newscientist.com/article/23 … e-equator/
Quote:

Candor Chasma is part of Valles Marineris, near the Candor Chaos region
ESA/DLR/FU Berlin (G. Neukum), CC BY-SA 3.0 IGO
A region of the Valles Marineris canyon system on Mars, one of the biggest in the solar system, appears to contain large amounts of water locked just beneath the surface, making it potentially useful for future astronauts.

I think that the possibility of Natural Hydrogen under the permafrost of Mars may be a very big thing to look for.

Done

Last edited by Void (2024-08-14 11:41:00)

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#1 2024-07-04 15:50:09

Water vapour atmosphere creation on Mars

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